A quantitative electromyographic analysis of masticatory muscle activity in usual daily life

OBJECTIVE: This study was designed to investigate whether a quantitative electromyographic (EMG) analysis with a special reference to the EMG amplitude at 98N bite force could reduce the influence of electrode relocation and to examine the reproducibility of masticatory muscle activity in usual daily life within individuals. SUBJECTS AND METHODS: In the first experiment, two sessions of surface EMG recording for masseter and anterior temporal muscles during tapping, and chewing gum and marshmallow were performed for 10 subjects with an interval of at least 1 week with electrode relocation. In the second experiment, two sessions of EMG recording during daytime (142 min, including mealtime) and sleep (142 min) were carried out for 10 subjects with an interval of at least 1 week. The average rectified EMG values were normalised with a special reference to the EMG amplitude induced by a 98N bite force. RESULTS: In the first experiment, high correlation coefficients and no significant differences in the mean normalised values of muscle activity were found between two sessions. Although the average rectified values showed high correlation coefficients, the mean masseter muscle activity while chewing gum was significantly different between two sessions. In addition, the variation in temporal muscle activity between two sessions while chewing gum was significantly smaller in the normalised values than in the average rectified ones. In the second experiment, less intra-individual variation in the normalised values of masticatory muscle activity between two sessions indicated the reproducibility. Normalised masticatory muscle activity showed less variation during mealtimes than during usual daytime and sleep. CONCLUSIONS: This quantitative EMG analysis could estimate the masticatory muscle activity by reducing the influences of electrode relocation, demonstrating an availability of this analysis for the evaluation of masticatory muscle activity in usual daily life.     

Non-invasive assessment of motor unit anatomy in jaw-elevator muscles

The estimation of fibre length in jaw-elevator muscles is important for modelling studies and clinical applications. The objective of this study was to identify, from multi-channel surface EMG recordings, the main innervation zone(s) of the superficial masseter and anterior temporalis muscles, and to estimate the fibre length of these muscles. Surface EMG signals were collected from 13 subjects with a 16-electrode linear array. The innervation zones of the masseter and anterior temporalis were identified and their variability intra- and inter-subject outlined. More than one main innervation zone location was identified in the masseter of all subjects and in the temporalis anterior of 12 subjects. Average estimated fibre lengths, for the right (left) side, were (mean+/-SD) 27.3+/-2.4 mm (27.0+/-1.7 mm) and 25.9+/-2.3 mm (26.6+/-1.6 mm), for the superficial masseter and temporalis anterior muscle, respectively. The range of innervation zone locations was up to approximately 50% of the fibre length, both within and between subjects. Fibre length estimates well matched with published data on cadavers. It was concluded that multi-channel surface EMG provides important and reliable information on the anatomy of single motor units in jaw-elevator muscles.     

Electromyographic evaluation of masseter and anterior temporalis muscles in patients with temporomandibular disorders following interocclusal appliance treatment

The purpose of this study is to evaluate the interocclusal appliance efficiency in patients with temporomandibular disorder (TMD), by using computerized electromyographic (EMG) evaluation in the rest position of the mandible. Twenty-two patients (male and female) with TMD symptoms, between 18 and 53 years of age, were examined. EMG evaluations were performed before the treatment and during the 90th, 120th and 150th day of using the interocclusal appliance therapy. In the 90th and 120th day, inserting canine guidance and group function disclusion, respectively, changed interocclusal appliance. The results showed that group function disclusion caused shorter EMG activity in the mandible rest position for the anterior temporalis muscle.     

杠杆定位手法对腰椎间盘突出症患者表面肌电信号及腰椎功能的影响

  目的  探讨杠杆定位手法对腰椎间盘突出症患者表面肌电信号及腰椎功能的影响。   方法  选择2018年7月—2019年6月收治的腰椎间盘突出症患者118例为研究对象,采用随机数字表法分为治疗组61例、对照组57例。对照组采用腰椎牵引治疗联合平面用力推拿手法,治疗组采用腰椎牵引治疗联合杠杆定位手法。治疗1个疗程后,比较2组患者临床疗效、表面肌电信号、腰椎功能等指标。   结果  治疗组腰椎间盘突出症患者总有效率(90.16%)高于对照组(75.44%,χ2=4.359, P < 0.05);患侧竖脊肌积分肌电值(IEMG)、均方根值(RMS)、中位频率值(MF)高于对照组[(27.45±4.23)V·s vs. (18.32±3.25)V·s,(32.45±5.12)μV vs. (21.34±4.20)μV,(82.25±10.21)Hz vs. (68.12±9.23)Hz,t=13.110、12.836、7.867, 均P < 0.05];多裂肌IEMG、RMG、MF高于对照组[(42.36±6.20)V·s vs. (25.45±4.62)V·s,(45.24±7.72)μV vs. (34.32±6.12)μV,(90.45±12.14)Hz vs. (75.32±9.24)Hz,t=16.707、8.476、7.578, 均P < 0.05)]; 腰腿痛程度、自理能力、提取重物、坐立状况、站立状况、睡眠质量评分低于对照组(均P < 0.05)。   结论   杠杆定位手法有助于改善腰椎间盘突出症患者核心肌群募集能力与耐疲劳性能,促进腰椎功能恢复,提高临床疗效。      

Pelvic floor electrical stimulation and muscles training: a combined rehabilitative approach for management of non-neuropathic urinary incontinence in children北大核心CSCD

PURPOSE To assess the efficacy of combined transcutaneous interferential (IF) electrical stimulation and pelvic floor muscle training through biofeedback on non-neuropathic urinary incontinence in children. METHODS This prospective study comprised of 46 anatomically and neurologically normal children (9 boys, 37 girls;mean age of 8.4±2.2 years old) with non-neuropathic urinary incontinence. All children were evaluated by kidney and bladder ultrasounds, uroflowmetry with electromyography (EMG), a complete voiding diary and a dysfunctional voiding scoring questionnaire at the baseline. Children were randomly allocated into two treatment groups including group A (n=23) who underwent biofeedback therapy in addition to IF electrical stimulation and group B (n=23) who received only biofeedback therapy. Re-evaluation was performed 6 months and one year after completion of the treatment sessions.     

Mandibular elevator muscles: physiology, action, and effect of dental occlusion

In spite of differences in embryologic origin, central nervous organization, and muscle fiber distribution, the physiology and action of mandibular elevator muscles are comparable to those of skeletal muscles of the limbs, back, and shoulder. They also share the same age-, sex-, and activity-related variations of muscular strength. With respect to pathogenesis, the type of muscular performance associated with the development of fatigue, discomfort, and pain in mandibular elevators seems to be influenced by the dental occlusion. Clinical research comparing the extent of occlusal contact in patients and controls as well as epidemiologic studies have shown reduced occlusal support to be a risk factor in the development of craniomandibular disorders. In healthy subjects with full natural dentition, occlusal support in the intercuspal position generally amounts to 12–14 pairs of contacting teeth, with predominance of contact on first and second molars. The extent of occlusal contact clearly affects electric muscle activity, bite force, jaw movements, and masticatory efficiency. Neurophysiologic evidence of receptor activity and reflex interaction with the basic motor programs of craniomandibular muscles tends to indicate that the peripheral occlusal control of the elevator muscles is provided by feedback from periodontal pressoreceptors. With stable intercuspal support, especially from posterior teeth, elevator muscles are activated strongly during biting and chewing with a high degree of force and masticatory efficiency, and with relatively short contractions, allowing for pauses. These variables of muscle contraction seem, in general, to strengthen the muscles and prevent discomfort. Therefore, occlusal stability keeps the muscles fit, and enables the masticatory system to meet its functional demands.     

The effects of masseter muscle pain on biting performance

The present study applied a standardized test food of known hardness to evaluate the biting performance of 20 female patients who had pain mainly in the masseter muscle during palpation. Another 20 women of a similar age group who were pain-free during examination served as controls. Electromyograms (EMG) of the masseter and sternocleidomastoid (SCM) muscles and the jaw position were recorded and measured when the subjects were biting through two types of test foods with known hardness (hard type, 20 kg hardness and extra-hard type, 60 kg hardness). Pressure-pain-threshold (PPT) values of both the patients and the normal subjects were obtained with an algometer. It was found that the PPT of the patients with pain was significantly lower and that the extra-hard food took more masseter muscle activity and more working side jaw movement in both the pain and the normal groups. During both hard and extra-hard food biting, a significantly longer duration of masseter muscle activity was found in pain patients while the total muscle activity was not significantly stronger. Strong correlation existed between SCM and masseter muscle activity during both hard and extra-hard food biting in the patient group, while such correlation was very weak in the normal group. In conclusion, painful masseter muscles required longer masseter and SCM muscle contraction time for breaking through a hard food of 20 kg and more, and co-activation of SCM and masseter muscles existed and was more evident when the food was harder or the pain was more severe.     

Enhancing surgical outcomes: The effects of speech therapy on a school-aged girl with Moebius Syndrome

PurposeMoebius Syndrome is a rare congenital neurological condition often characterized by multiple cranial nerve involvement. This case study presents an eight-year old girl with Moebius Syndrome (MC) who received 30 sessions of speech therapy. This occurred after presenting to clinic 11 months after left facial reanimation with gracilis thigh muscle transfer surgery. On examination, only flickers of left facial movement were observed. There was no movement on the right side of the face. As a consequence of the minimal movement, MC presented with drooling and unintelligible speech. The purpose of speech therapy was three fold: minimise the pooling of saliva, improve the placement of the articulators so that articulation of speech sounds would be more accurate, and gain advances in overall intelligibility.MethodsTherapy focussed on speech, facial movement and saliva management using a combination of speech drills, evidence-based articulation therapies, facial exercises with surface electromyography biofeedback, self-awareness training and compensatory saliva management strategies.ResultsAfter a course of 30 one-hour speech therapy sessions, substantial improvements were seen in speech sound accuracy, overall intelligibility, facial movement and saliva control.ConclusionsThe combination of surgery and speech therapy led to functional gains that surgery alone did not achieve. The impact of speech therapy on surgical outcomes in individuals with Moebius syndrome deserves further investigation.